Saturday, January 28, 2012

Assessing and Fixing the Damaged Front End

If you read my last post, you'll learn that I wrecked the front end of the car in a bad spin at the last SCCA race at Thunderhill in July 2011.

Damage Assessment

I got the car home and got the front up on jackstands and started to assess damage.  Here is what I found.

1. Upper control arm bent:

2. Lower Control Arm very slightly bent (forgot to get picture).  I probably could have re-used it but it would have affected how much camber could be adjusted.

3. Front Subframe bent badly.  Here are a few pics illustrating the damage:
- Subframe Lower Control Arm rear mounting tab bent:

- Subframe Lower Control Arm front mounting tab bent:
4. Front wheel bent:

I had already changed the front subframe once before while building the car b/c the driver side mounting tabs for the steering rack had been bent at one point in the car's life.  It isn't that difficult to do but is a bit time consuming and not fun.  I decided to tackle the repair myself so I started sourcing parts.  "Where to source these parts?" you might be thinking.  The answer is craigslist. :-)

Most of the used parts sourced for this car came from craigslist.  So I turned there again.  It seems like there is always somebody local parting out a Miata on Craigslist.  Since the parts are local, shipping costs are eliminated.  

I decided to upgrade the front subframe to the one from the 94-97 Miatas.  These cars came equipped with more bracing from the factory on the front and rear subframes.  You technically could add these braces to the original subframe of the 90-93 cars but that would require more work on my part.  When I started looking for parts, I discovered that a fellow racer had the parts I needed.  He cut me an awesome deal at $100 for the front subframe, spindle and lower control arm.  I didn't need the upper since I had a spare.  I sourced  a new wheel from our local race tire supplier and series sponsor - AIM Tire.

So I picked up the parts and started wrenching to get the car ready for the next race.  I replaced the subframe and control arms.  I didn't replace the spindle at this time because a I couldn't get the ball joint separated so I left it alone since I had replaced the ball joint when I built the car.

Here is a comparison of a bent subframe the straight, un-bent replacement.  The bent subframe is on top.  The replacement is on the bottom.  The control arm mounting tabs were bent a good 1/4".

If you never replaced a front subframe on a Miata, it isn't particularly difficult.  It took me the better part of a day to do it 4-6 hours.  If you want specifics, please contact me and I can prepare a write-up with pics.

Do you think I got it right?  Sadly, no....

Once the car was back together, I brought it over to TFB Performance to get the car corner balanced and aligned.  Here is where we discovered that I had not replaced ALL of the bent parts.  We couldn't get more than -1.5* of camber on the passenger front.  Turns out the spindle and the ball joint were also bent.  I never even knew those parts could bend....  Thankfully, TFB does a lot of Miatas and had the parts in stock.  He installed a new ball joint and a used spindle.  I spent about $700 in total on this repair.  Expensive mistake but it could have been worse.

If you are curious about how to diagnose a bent ball joint.  Here is a video I took repeating the diagnostic procedure that TFB had done in the shop.  Basically, put a socket on the ball joint, put pressure so that the ball joint is pushed downward or outward so that it is against the outer edge that it sits in, then turn the wrench as if you were tightening the nut.  Hopefully the video makes sense of this:

Frustrating repair but it got done.  When's the next race?

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